| Institution: | 1. Slovak Academy of Sciences, Institute of Materials Research, Watsonova 47, 040 01 Kosice, Slovakia;2. Faculty of Mining, Ecology, Process Control and Geotechnology, Technical University of Kosice, Letna 9, 042 00 Kosice, Slovakia
Bulgarian Academy of Sciences, Institute of Catalysis, Acad. G. Bonchev St, BU-1113 Sofia, Bulgaria;3. Faculty of Mining, Ecology, Process Control and Geotechnology, Technical University of Kosice, Letna 9, 042 00 Kosice, Slovakia |
| Abstract: | Neodymium niobate NdNbO4 (NNO) and tantalate NdTaO4 (NTO) thin films (~100 nm) were prepared by sol-gel/spin-coating process on Al2O3 substrate with LaNbO4/PbZrO3 interlayer and annealing at 1000°C. Surface chemistry was investigated by X-ray photoelectron spectroscopy (XPS). The core-level XPS studies of sol-gel NNO and NTO were performed for the first time. The binding energy differences Δ(O―Nb) and Δ(O―Ta) were used to characterize average energies of Nb―O bonding in NNO (322.9 eV) and Ta―O bonding in NTO (504.2 eV). The XPS demonstrated single valence state of Nd (Nd3+) in precursors. Nd concentration (at. %) decreases from 22% in precursors to 7% in films considering the substrate contains C, Al, Si, Pb, and Zr elements (37%) at Nb or Ta (5%) and O (51%). The X-ray diffraction analyses verified formation of the monoclinic (M-NdNbO4 or M′-NdTaO4), orthorhombic (O-NdNbO4) and tetragonal (T-NdTaO4) phases in precursors and films. Single valence state of Nd3+ was confirmed in these films designed for the application in environmental electrolytic thin film devices. |
